Why HIIT Works

Image courtesy of F45 Rosebery

Image courtesy of F45 Rosebery

Unless you came down in the last shower, you will definitely have heard all the hype surrounding HIIT training. You've probably got loads of questions so I have taken it upon myself to 'hit' you up with loads of answers...

What is HIIT?

HIIT is an acronym for High Intensity Interval Training, a training technique that involves going 'hell for leather' for a set period of time, followed by short period of recovery. The continued alternating periods of high and low-intensity activity generally last for a duration of no more than 20 minutes although the session may be much shorter than that. 

A HIIT session may indeed involve any type or combination of activities that force the heart rate to rise substantially as exercise reaches a maximum capacity. 

Why is HIIT Beneficial?

Accompanying all of the hype is some serious science supporting HIIT as a protocol:

- Greater overall caloric expenditure - while it's a rough statement, body weight management depends upon 'calories in' vs 'calories out'. Compared to continuous aerobic workouts, HIIT training actually:

  • Demands more fuel DURING the performance of the workout due to the greater stress placed on the body; 
  • Burns a greater amount of calories AFTER the workout to restore balance - this is know as exercise post-oxygen consumption (EPOC).

- HIIT is far less boring - if you have nightmares of spending hours walking or jogging on treadmills, then HIIT is your answer. One of the greatest determinants of exercise compliance in the long term is whether you are enjoying it. If you know you only need to muster the heart for a 15 minute slog session, possibly involving a spew, you're much more likely to stay committed, particularly when you see results. 

- HIIT is more time-efficient - flowing on from the last point, the short sessions of a HIIT workout blank that ever-present excuse "I have no time". Remember, a HIIT session can be as short as 5-10 minutes and anyone that can't find that in their schedule is taking the piss!

- No equipment needed AND do it anywhere - illustrating HIIT's true flexibility and user-friendliness, is that it requires zero equipment. Sure, rowers, bikes and skipping ropes can add a new dimension but they are not a necessity. Lunges, sprints and burpees can be just as effective. Performed in a park or pool, you're no longer hinged to a treadmill or stuck inside a gym. 


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As with all exercise programs, if you have been relatively inactive for a while, you should start by visiting your GP and getting a clearance to commence working out. AND, while the technique HIIT involves high intensity exercise, you should definitely NOT take to the sprint track for the first time in 20 years and pretend you're Usain Bolt. That will only end in one way... badly. 

Once you have built up a base level of fitness, you've got two main options depending on your previous exercise history, level of motivation and experience. 

Option 1 - join a class: this would definitely be my suggested option if you like group activity, prefer to be told what to do or need a little assistance with motivation. Specialised centres like F45 or specialised HIIT classes within more general gyms are a perfect introduction. You'll have an instructor to guide and motivate you and perhaps even make a few friends along the way, as I have. 

Option 2: create your own workout: using whatever is available to you, you can design your own program to include body weight, free weights, and non-resistance exercises. Literally millions of exercise combinations are possible and this option is recommended if you're more advanced, prefer training alone, are very self-motivated or enjoy getting outdoors. 

Based around a 15-20 minute total session duration, you could try either of the following:

  • Sprint, row, swim, skip or stair climb for:
    • 15 seconds and walk/jog for 30 seconds.
    • 30 seconds and walk/jog for 60 seconds. 
    • 60 seconds and walk/jog for 90-120 seconds. 
  • Individually or in combination, perform squats, benchpress, deadlifts, pull ups, box jumps or burpees for one minute and then rest for one minute.

Whatever the case, the aim is not to pace yourself. You're going for maximum exhaustion in the shortest time possible. High intensity is not a "walk in the park", mind the pun.


It's rare that a fad stands the test of time but my prediction is that HIIT training is here to stay. Unlike dieting, the science is clear in it being of huge benefit to our overall health. Steady-state cardio still has its place for those wanting to improve their aerobic capacity but in a world that's driven by minimum time input, maximum return, HIIT just fits the bill. 

Stick your comments or questions below. Be strong, Jase